Viscosity index improvers



United States Patent 3,509,056 VISCOSITY INDEX IMPROVERS Thomas H.Shepherd, Hopewell, N.J., assignor to Princeton Chemical Research, Inc.,Princeton, N.J., a corporation of New Jersey N Drawing.Continuation-in-part of applications Ser. No. 283,672, May 28, 1963, andSer. No. 357,294, Apr. 3, 1964. This application Oct. 10, 1966, Ser. No.585,299

Int. Cl. C10m 1/18 US. Cl. 252-59 5 Claims ABSTRACT OF THE DISCLOSUREViscosity index improver for lubricating oils in the form of pureoil-soluble hydrocarbon polymers having a molecular weight between about50,000 and 2,000,000 composed of a hydrocarbon chain having a number ofalternate stereoregular and amorphous segments, the amorphous segmentscontributing at least 50% of the molecular Weight of the polymer givingit its oil-solubility characteristics and the stereoregular segmentsbeing present in sufiicient quantity to give the polymer a viscosityindex improving efiiciency of at least 1.0 without destroying theoil-solubility characteristics. The stereoregular segments arepreferably of the group of polybutene-l, polypropylene, poly-4-methyl,pentene-l, poly-3-methyl butene-l, polystyrene, polypropylene-butene-lcopolymers, polypropylene-styrene copolymers, polyethyleneethylenecopolymers, ethylene-butene-l copolymers and polybuten-l. The amorphoussegments are alpha olefin polymers. Preferably the polymer is ater-polymer additionally containing up to 25 mol percent of a higheralpha olefin. Most preferably the polymer is a ter-polymer havingisotactic polypropylene segments and amorphous segments of a polymer ofa lower alpha olefin and additionally containing 120 mol percent of ahigher alpha olefin. The improver is generally dissolved in petroleumlubricating oil in amount from 1 to 20%.

This invention relates to viscosity index improvers for lubricating oilsand is a continuation-in-part of my copending applications Ser. No.283,672, filed May 28, 1963, now abandoned, and Ser. No. 357,294, filedApr. 3, 1964. The invention more particularly relates to certainhydrocarbon block copolymers which are useful as viscosity indeximprovers for lubricating oils; lubricating oils of improved viscosityindex containing these polymers, and to a process for improvingviscosity characteristics of such oils with the use of these polymers.

Ordinary lubricating oils, and particularly petroleum oils as areconventionally used in internal combustion engines generally show adecrease in viscosity with increasing temperatures. If the internalcombustion engine or the machinery containing the oil is to be initiallystarted and operated, at a low temperature, as for example in the colderclimates or in the winter, it is necessary to use a thinner, lighterweight oil if the oil is to have initial fluidity at the low temperaturefor starting an initial lubrication. Such oils are commonly availablefor example, as winter-grade oil, such as SAE weight or lower. As theengine operates and heats up the oil, these oils become thinner, and athigher operating temperatures the thinner, lighter weight oil may nothave sufiicient viscosity for optimum lubrication. Furthermore, inwarmer weather, such as in summer, the lighter weight is not suitable,and it is necessary to change to a heavier weight oil, as for example a20 or 30 weight oil. This characteristic of the oil to change itsviscosity with temperature is measured by a value referred to asviscosity index.

In order to improve the viscosity index of conventional petroleumlubricating oils, and thus obtain an oil, such as the presentcommercially available multi-grade, as for example the 10-30 weightoils, it has been proposed to add to the oil certain oil solublepolymers which act as viscosity index improvers. The efiiciency(referred to as E) of the viscosity index improveris measured as theratio of the specific viscosity of the oil containing the improver at210 F., to specific viscosity at F. An E value higher than 1 isgenerally desirable as an oil which has a reduced tendency to thin outwith increase in temperature is necessary to meet the engine lubricationneeds at higher operating temperatures. The viscosity improvingefficiency, E of commercial products generally ranges from 1.0 to 1.5.

The thickening power or ability to increase the viscosity of an oil as afunction of concentration is also an important factor of the viscosityindex improvers. Generally, the small amount of the viscosity indeximprover which is required to achieve a desired specification in thefinished oil, the more desirable the improver. For commerciallyattractive products 0.4 to 2, and preferably 0.8 to 1.5 weight percentof the improver should be able to achieve 11 to 12 centistokes viscosityat 210 F. with l0W30 base oils.

It is additionally often necessary to depress the pour point of oils,such as lubricating oils, so that the same may function properly at lowtemperatures. Various pour point depressants are known and widely used,and some viscosity index improvers additionally act as pour pointdepressants.

The methacrylate polymers, such as polymethacrylate esters are presentlymost commonly commercially used as viscosity index improvers forlubricating oils. Additionially, polyisobutylene and polyfumarate estersare use While these viscosity index improvers effectively improve theviscosity index of the lubricating oil, and thus overcome theabove-mentioned problem and allow the marketing of a multi-grade oil,which is suitable for allseason uses, having an initial low enoughviscosity for starting in cold Weather use and yet has sutficientviscosity at higher temperatures, the same have a number ofdisadvantages, such as high initial cost and tendency to undergo thermaldepolymerization with a resultant limited life and poor shear stability.

One object of this invention is the provision of viscosity improvers forlubricating oils without the abovementioned disadvantages.

A further object of this invention is viscosity index lmprovers havinghigh efiiciency, excellent compatibility to the oil and its additivesand high thermal stability.

A further object of this invention is a superior oil viscosity indeximprover which may be produced at a relatively lower cost.

These and still further objects will become apparent from the followingdescription:

In accordance with the invention I have discovered that certainsubstantially pure oil-soluble hydrocarbon polymers of a molecularweight of between about 50,000 and 2,000,000 composed of a hydrocarbonchain having a number of alternate stereo-regular and amorphous segmentsconstitute highly efiicient viscosity index improvers for lubricatingoil, which overcome many of the disadvantages of the prior knownimprovers. The viscosity improvers in accordance with the invention arecompletely compatible to the lubricating oil and its conventionaladditives in its normal use environment; are highly stable under therigors of temperature and use, and may be readily produced.

The molecular weight of the polymer is the molecular weight as measuredby intrinsic viscosity. The stereoregular segments constitute polymerblocks composed of linear polymer chains consisting substantially solelyof methylene and branched chains of methylene units or hydrocarbon ringswhich are arranged in an orderly spatial distribution to give thepolymer its stereoregular characteristics. The molecular arrangement ofhydrocarbon polymers which render the same stereoregular in nature iswell known in the art, as are the methods for polymerizing a hydrocarboninto such an arrangement.

The amorphous segments are simply amorphous hydrocarbon blocks or chainsand must contribute at least 50% of the molecular weight of thehydrocarbon polymer. The stereoregular segments must be present insufficient quantity to give the polymer a viscosity index improvingefficiency of at least 1.0 as measured in the conventional manner, asfor example in connection with an SAE 20/30 weight petroleum oil.

The stereoregular segments or blocks must have a molecular configurationwhich would give the same certain oil solubility characteristics if theycollectively existed apart per se as a polymer, ie if all the amorphoussegments were removed from the polymer chain in accordance with theinvention and if the stereoregular segments were rejoined together as apolymer. Under these assumed conditions the stereoregular blocks orsegments Would have to form a polymer which would be insoluble in oil ata temperature below C., and preferably insoluble at a temperature below20 C. As the chain of the polymer in accordance with the invention iscomposed of the stereoregular and amorphous segments which may also bereferred to as blocks, the polymer may be considered as a blockcopolymer and is sometimes referred to herein as such.

As used herein, the term oil insolubility is intended to designatesolubility of less than .1% by weight in an SAE SW-paraffinic stock andcomplete oil solubility is intended to designate solubility of at least10% by weight in an SAE SW-parafiinic stock.

Most preferably the stereoregular polymer blocks or segments areisotactic polypropylene and/or polybutene-l blocks. Additionally otherstereoregular polymer blocks having the above-set forth characteristicsare applicable. Examples of such stereoregular polymer blocks includestereo-specifically polymerized polymers alpha olefins having from 3 to8 carbon atoms per molecule such as: of 4 methylpentene-l,3 methylbutene-l, and styrene; copolymers of propylene and butene-l containing,for example, from 5-30 mol percent of butene-l, and preferably from5-2-0 mol percent of butene-l; stereo-specifically polymerizedcopolymers of propylene and styrene containing, for example -40 molpercent of styrene and preferably from -30 mol percent of styrene;stereo-specifically polymerized copolymers of propylene and ethylenecontaining from 5-25 of ethylene and preferably from 10-20 mol percentof ethylene; stereo-specifically polymerized copolymers of ethylene andbutene-l containing, for example, 5-30 mol percent of butene-l andpreferably 15-25 mol percent butene-l and isotactic polypentene.

The amorphous blocks as mentioned must contribute at least 50% of thetotal molecular weight of the polymer in accordance with the inventionand must be of such a nature that if collectively joined together as apolymer per se Without the stereoregular blocks or segments, it wouldform a polymer soluble in oil at a temperature of '20 C. and above, andpreferably at a temperature of 30 C. and above.

As used herein, the designation of the amorphous blocks as being solublein oil and oil soluble designates a solubility of at least 10% by weightin an SAE 5W paraflinic oil.

*Examples of the amorphous hydrocarbon polymer blocks include copolymersof propylene and butene-l containing from 30-70 mol percent of butene-l;atactic polybutene-l; copolymers of ethylene and butene-l containingfrom 40-70 mol percent of butene-l; copolymers of propylene and (Q-Calpha olefins containing from 30-90 mol percent of the higheralpha-olefins; copolymers of propylene and ethylene containing from25-7-0 mol percent ethylene and preferably from 30-60 mol percent ofethylene; interpolymers of C -C alpha olefins; terpolymers of C -C alphaolefins; copolymers of ethylene, and C -C alpha olefins containing from30- mol percent of higher olefins, and C -C alpha-olefin homopolymers.

Most conveniently, the amorphous hydrocarbon polymer blocks are formedby the coor interpolymerization of the monomer or monomers used to formthe stereoregular block with one or more differing alpha-olefins, as forexample having a molecular weight between (I -C Alternately, theamorphous hydrocarbon polymer block may be formed from the same monomerused to form the stereoregular block under polymerization conditions,however, which will not produce a stereoregular polymer, but which willproduce the required amorphous oil soluble block.

The molecular weights and oil solubility characteristics of thesteroregular and amorphous blocks specified herein and in the claimsare, as mentioned, those that the blocks per so would have asindependent unattached polymers.

The oil soluble hydrocarbon polymers containing the number of alternatestereoregular and amorphous segments are produced by the well knownpolymerization techniques, and preferably from monomer mixtures whichwill form the stereoregular and amorphous blocks or segments, and thepolymerization may be achieved utilizing batch or continuous techniques.Polymerization may be effected using highly dispersed stereo-specificcatalysts, as for example, the well known Ziegler catalyst formed, forexample, from organo-metallic compounds such as aluminum trialkyls oralkyl aluminum halides, and transition metal salts, as for examplehalides or alcoholates. Examples of such catalyst systems includealuminum triethyl with titanium or vandium tetraor trichloride;diethylaluminum chloride with titanium or vanadium tetraor trichloride;butyl lithium with titanium tetraor trichloride, or vanadium tetraortrichloride, or the like. The polymerization is effected in an inerthydrocarbon solvent, as for example, normal heptane or pentane under aninert atmosphere, as for example nitrogen at moderate temperatures, asfor example between about 30 and 150 C., and preferably between about 80and C. at normal or slightly elevated pressure. The polymerizationshould be effected so that both the amorphous and stereospecificsegments are formed. Preferably the hydrocarbon polymers forming theviscosity index improvers in accordance with the invention are formedfrom monomer mixtures which will form the stereoregular and amorphoussegments or blocks. The polymerization may be effected as a continuousprocess or as a batch process.

It is possible to produce the viscosity index improver polymer inaccordance with the invention by, for example, first effecting thepolymerization under conditions which will favor formation of thestereoregular blocks or segments, which conditions are, of course, knownper se in the art, and to continue the polymerization under the knownconditions which will favor the formation of the amorphous segments orblocks. For this purpose the polymerization may be effected in the samereaction zone using, for example the batch method, or may be effected intwo separate reaction zones with the stereoregular chain passing intothe second reaction zone for continuation of the polymerization with theformation of the amorphous segments. As mentioned, however, it ispreferable to form the polymers from monomer mixtures which form bothstereoregular and amorphous blocks.

Utilization may be made of the different reactivities of differentmonomers of the mixture to form the stereoregular and amorphoussegments. Thus, for example,

when using propylene and butene-l as the monomers the reactivity of thepropylene will generally initially favor the formation of isotacticpolypropylene segments. Polymerization of the amorphous blocks orsegments will also occur in increasing amounts without any requirementfor temperature, or any other adjustments.

The polymerization reaction may be discontinued and the polymerrecovered and isolated in the conventional manner, as for example bywashing with ethylene glycol to remove the catalyst residue andprecipitating the polymer with methanol, or distilling off the solventleaving the polymer residue.

For continuous operation the polymerization may be basically effected inthe same manner and under the same conditions with, for example, acontinuous pump ing of the catalyst system. It is possible, forinstance, to continuously pump the catalyst solution in series throughtwo reactor stages with the necessary residence time in each stage andwith each stage being effected under conditions to form thestereoregular blocks or segments.

The polymers obtained in accordance with the invention are admixed withthe conventional lubricating oils in the conventional manner asviscosity index improvers. Thus the polymers may be added to thelubricating oils in amounts of 0.1 to 30, and preferably 0.3 to 10, andmost preferably 0.5-% by weight.

The oils may be of any of the known or conventional lubricating oils asfor example, petroleum lubricating oils of the conventional weights usedin internal combustion, such as automotive engines. The oil, forexample, may have a viscosity so that after the addition of the polymerin accordance with the invention, the oil will have an SAE rating ofW-30.

The oil may, of course, contain all the known and conventionaladditives, such as the conventional detergents, dispersing aids, pourpoint depressants, anti-oxidants, viscosity improvers, or the like.

In addition, to use with conventional petroleum lubricating oils, which,for example, consist of conventional base stocks or base stock blendswith or without conventional additives, the polymers in accordance withthe invention, may be added to any other liquid, hydrocarbons forviscosity index improvement, as for example synthetic lubricating oils,such as the Fischer-Tropsch produced oils, or the like.

Viscosity index improvers are often marketed as concentrated solutionsin a base oil, as for example in concentrations between 10-30, andpreferably 30% by weight, which is blended with the lubricating oil. Thebase oil of the concentrate may, for example, be a 100 S.U.S. paraffinicoil. In connection with polymers in accordance with the inventioncontaining amorphous hydrocarbon polymer blocks formed from lower alphaolefins, ifi. alpha olefins containing up to 4 carbon atoms, the samemay tend to unduly thicken the base oil rendering handling of theconcentrate difficult.

In accordance with a preferred embodiment of the invention, it has beenfound that this tendency to unduly thicken the base oil of theconcentrate may be avoided if the polymer is formed as a terpolymeradditionally containing components formed from 0.5 to mol percent andpreferably from 1 to 20 mol percent based on the total monomer chargedof a higher alpha olefin containing 5-25, and preferably 7l5 carbonatoms. The higher alpha olefin should be present in the polymerizationmixture before complete formation of the polymer and should bepreferably present during the formation of the isotatic blocks. Examplesof higher alpha olefins which may be used include n-pentene-l,n-hexene-l, n-heptene-l, noctene-l, n-nonene-l, n-decene-l,n-dodecene-l, n-octadecene-l, and mixtures of alpha olefins available asfractions, as for example C -C alpha olefin fractions, C -C alpha olefinfractions, C C alpha olefin fractions, and C -C alpha olefin fractions.Branched alpha olefins, such as 3-methylbutene-l, 4-methylpentene-l,isobutylethylene, neopentylethylene, and isoarnylethylene may also beused.

It is believed that the alpha olefin in the formation of the terpolymerrandomyl distributes in or adjacent the isotactic polymer blocks, or inor adjacent both the isotatic and amorphous polymer blocks. Theterpolymer, having the higher alpha olefin component, however, enablesthe preparation of pourable concentrated oil solutions of the polymerwithout unduly affecting the efiiciency of the polymer as a viscosityindex improver.

It is believed that the polymers in accordance with the inventionperform their viscosity index improving function by the initialdissolution of the amorphous block in the oil at a lower temperaturewhich holds the entire polymer in solution while actually thestereoregular block remains substantially unsolvated but progressivelyis solvated in the oil with a temperature increase causing the desiredcompensation for the natural decrease in viscosity with increasingtemperatures. It is thus believed that the unique oil-solubilitycharacteristics of polypropylene make it preferable as the stereoregularpolymer block in accordance with the invention. Other usablestereoregular polymer blocks, are for example, isotactic polybutene-l,or isotactic polypentene-l, which latter dissolves in oil at about 20 C.and is completely soluble at 30 C. so that the same is not as desirableas isotactic polybutene-l for normal lubricating oil use, but is ahighly desirable component of a polymer useful as a viscosity indeximprover for low temperature applications.

In view of the fact that the polymers in accordance with the inventionare substantially pure hydrocarbon products, they are completelycompatible with the oils and any additive which, in turn, is compatiblewith the oil itself. Furthermore, the products may be considered ashlessas they by conventional catalyst removal techniques, such as alcoholwashing, may be reduced to an ash content below 0.1% which is preferablefor the use herein. As compared with the conventional viscosity indeximprovers, as for example, the methacrylate polymers, the polymers inaccordance with the invention are highly stable in their environmentaluse, do not undergo thermal depolymerization and have high shearstability. Furthermore, the polymers may be easily, readily, andinexpensively produced by the known polymerization techniques.

For the highest V.I. improving efficiency, the relative length of theoil-soluble block should be the minimum required to hold the polymer insolution at a lower temperature, as for example at 0 F. This isdependent, to a degree, on the type of the oil stock in connection withwhich the improver is being used. In general, the molecular weight ofthe amorphous hydrocarbon polymer block should be at least 50% of themolecular weight of the stereoregular block with stereoregular andamorphous segments of approximate equal length being satisfactory formost purposes.

The following examples are given by way of illustration and notlimitation:

EXAMPLE 1 To a one-liter autoclave under a dry nitrogen atmosphere wasadded a solution of 1.9 ml. (15 mmols) of diethyl aluminum chloride in350 ml. of n-heptene. A titanium trichloride catalyst (1.5 g.)containing /3 mol of aluminum trichloride per mol to titaniumtrichloride was then added to the autoclave, and the temperature wasadjusted to 50 C. 50 grams of butene-l was charged to the autoclave, andpolymerization was allowed to continue at that temperature for 45minutes. grams of a mixture containing 53 mol percent propylene and 47mol percent butene-l was then charged, the reactor was heated to C. overa 30-minute period, and was held at that temperature an additional 30minutes. The autoclave was then cooled and vented. The viscous solutionin the autoclave was removed, washed with etyhelne glycol and water toremove catalyst residue and the polymer was isolated by precipitationwith methanol. After drying in a vacuum oven, 98 g. of polymer wasobtained. The polymer was completely soluble in warm heptane and showeda melt index (190 C., 2160 g. load) of 4.0. The specific viscosity of a0.5% solution of the polymer dissolved in an SAE Weight Mid-Continentstock was 1.4 at 100 F. and 1.75 at 210 F. Calculation of the ratiogives a V.I. improving efiiciency of 1.25. In shear stability testsconducted on 1.0% solutions of the polymer in a naphthenic base stock,the polymer was greatly superior to commercial methacrylate V.I.improvers.

EXAMPLE 2 The catalyst was the same as that used in Example 1. A mixturecontaining 18 g. of styrene and g. of propylene was added to theautoclave at 60 C. Polymerization was allowed to proceed one hour. Asmall sample of polymer was removed at this point. Infra-red analysisindicated that the polymer contained 16 mol percent styrene. 100 gramsof an equimolar mixture of propylene and butene-l was then charged andthe temperature was varied to 100 C. over a 30-minute period, and waskept at that temperature for an additional 30 minutes. The polymer wasworked up as in Example 1. 84 grams of polymer having a melt index of11.9, was obtained. A 1% solution of this polymer in a solvent refinedSAE 30 weight Mid-Continent stock showed a V.I. improving efiiciency of1.2.

EXAMPLE 3 To a 1 liter autoclave under a dry nitrogen atmosphere wasadded a solution of 2.2 ml. (20 mmols) of titanium tetrachloride in 250ml. of a straight mineral oil (Texaco Regal Oil B) previously treatedwith molecular sieves. A solution of 1 ml. (7.5 mmols) of triethylaluminum in 100 ml. n-heptane was added and the mixture was warmed to180 C. over an hour. The autoclave was then cooled to C. and 7.0 ml.(52.5 mmols) of triethyl aluminum in 50 ml. of mineral oil was added.Butene-l (50 g.) was charged and polymerization was allowed to proceed30 minutes, at which time the pressure dropped from 50 lbs. gauge toatmospheric pressure. A mixture (100 g.) containing equal molar amountsof propylene and butene- 1 was charged, and polymerization was allowedto continue as the temperature was increased to 100 C. over 45 minutes.The autoclave was then cooled and vented. The viscous solution waswashed with ethylene glycol and water. The heptane was stripped invacuo. A viscous residue weighing 368 g. and containing 128 g. ofpolymer was obtained. Dilution of a sample to 1% concentration in atypical Mid-Continent SAE 10 weight stock gave a solution which showed aviscosity improving efliciency of 1.22.

EXAMPLE 4 Example 1 is repeated and the temperature of thepolymerization raised to 110 C. and the propylene butene-l charged afterthe initial butene-l had polymerized to isotactic butene-l with amolecular weight of about 100,000. The polymerization at the highertemperature was discontinued when the amorphous copolymer block ofpropylene and butene-l had reached a molecular weight between about200,000-300,000. A 1% solution of the polymer formed acted as aviscosity index improver when used as a 1% solution in a conventionallubricating oil (Texaco Regal Oil B).

EXAMPLE 5 Polymerization is effected in the manner described in Example1 using the catalyst system described therein with, however, a mixtureof propylene and butene-l. as the monomer containing amounts ofpropylene ranging between 25-75 mol percent propylene. In each case anexcellent viscosity index improver for lubricating oil is formed.

EXAMPLE 6 Example 5 is repeated except that in place of the mixture ofpropylene and butene-l, a mixture of propylene and ethylene containingabout 30-60 mol percent of ethylene is introduced in the secondpolymerization stage where the polymerization is effected at the highertemperature.

EXAMPLE 7 Example 6 is repeated, except in the second stage instead ofthe propylene-ethylene mixture, an alpha-olefin having an averagemolecular weight between C C is used.

EXAMPLE 8 Example 1 is repeated but in place of the butene-l, a mixtureof ethylene and butene-l containing 40-70 mol percent of butene-l isintroduced. The polymerization is continued until the amorphousethylene-butene-l copolymer is built up to a molecular weight of200,000.

EXAMPLE 9 Example 8 is repeated, except that the polymerization iscontinued at the higher temperature of 110 C. by introducing a mixtureof propylene and C -C alpha olefins containing about 30-90 mol percentof the C -C alpha olefins. The polymerization of the propylene-higheralpha olefin amorphous block was continued to a molecular weight of200,000-300,000.

EXAMPLE 10 Example 1 is repeated but the butene-l initially charged isadmixed with -95 mol percent of propylene with the polymerization of thestereo-specific copolymer continued to a molecular weight of about100,000. The mixture containing the larger amount of butene-l, i.e. the47 mol percent was then introduced and the polymerization continued at ahigher temperature until the amorphous polymer block reached a molecularweight of 300,000.

EXAMPLE 11 Example 2 is repeated with the initial stereo-specificpolymerization being effected to a molecular weight of 90,000.Thereafter the polymerization is continued at the increased temperatureof C. utilizing propylene and an alpha olefin of an average molecularweight of C -C in substantially equal parts. The polymerization of theamorphous copolymer is discontinued after a molecular weight of 150,000is achieved.

EXAMPLE 12 EXAMPLE 13 Example 10 is repeated except that ethylene isused in place of the propylene.

EXAMPLE 14 Example 1 is repeated initially using, however, pentene- 1 inplace of the butene-l to form an isotactic polypentene- 1 block in placeof the isotactic polybutene-l block. Additionally, in place of theamorphous propylene-butene-l copolymer block an atactic polybutene-lblock may be formed.

EXAMPLE 15 To a one-gallon autoclave, under a dry nitrogen atrnosphereis added a solution of 3.7 ml. (30 mmols.) of diethyl aluminum chloridein one liter of heptane. A titanium trichloride catalyst (3.0 g.)containing /3 mol of aluminum trichloride per mol of titaniumtrichloride is added and the temperature is raised to 65 C. Sixteengrams of hexene-l is added followed immediately by 56 g. of

butene-l. Polymerization is allowed to continue 30 minutes at 65 C. Thereactor is then vented and 60 g. of a butene-propylene mixturecontaining 52 mol percent propylene is charged. Polymerization isallowed to proceed an additional 60 minutes at 65 C. The autoclave isthen emptied and polymer is precipitated from the viscous heptanesolution with isopropanol. After drying, 85 grams of polymer areobtained. This polymer, as a 1% solution in a 100 S.U.S. parafiinic oil,exhibits a viscosity index improving efficiency of 1.23, and a 10%solution of the polymer in the same base oil is readily pourable. Thehexene-l constitutes 7.9 mol percent of the monomer charge.

EXAMPLE 16 To a one-gallon autoclave was charged a solution of 5.1 ml.(40 mmols) of diethyl aluminum chloride in 2 l. of n-heptane. Titaniumtrichloride (4.0 g.) containing /3 mol of AlCl per mol of TiCl was addedand the tem' perature was raised to 75 C. A C -C alpha olefin fraction(50 g.) was added followed immediately by 200 g. of a butene-l-propylenemixture containing 52 mol percent propylene. Polymerization was allowedto continue two hours, whereupon the pressure in the reaction haddropped to less than p.s.i. The polymer was isolated by conventionaltechniques. After drying, 163 grams of polymer was obtained. A 1%solution of this polymer in a 100 S.U.S. parafiinic oil showing aviscosity index improving efficiency of 1.28 and a 10% solution of thepolymer in the same base stock was readily pourable. The molecularweight of the polymer was estimated to be 800,000 from dilute solutionviscosity measurements. The C7-C9 alpha olefin fraction constituted 10mol percent of the monomer charge.

EXAMPLE 17 To a one-gallon autoclave, under a nitrogen atmosphere, wasadded 2 liters of heptane containing 3.0 g. of TiCl /3 AlCl and 3.75 ml.of diethyl aluminum chloride. The reactor was closed and the temperaturewas raised to 60 C. 4-methyl pentene-l was then pumped into the reactorat a rate of 5 g./ minute, and butene-l was pumped into the reactor at arate of 2 g./minute. After 20 minutes, the addition of 4-methylpentene-l was terminated. The addition of butene-l was allowed tocontinue for a total of 50 minutes. After an additional hour ofpolymerization, the reaction was terminated by the addition of methanol.After isolating and drying in the conventional manner, 71 g. of a blockcopolymer (4-methyl pentene-l-butene-l copolymer) having a molecularweight of 900,000 was obtained.

A 1% solution of this polymer in a 100 S.U.S. neutral parafiinic oilafter standing three days showed a viscosity index improving efiiciencyof 1.99.

EXAMPLE 18 Example 17 was repeated, using styrene in place of 4-methylpentene-l. The reaction was carried out at 80 C. After 2 hours, 45 g. ofa block copolymer (styrenebutene-l copolymer) was obtained which showeda viscosity index improving efficiency of 1.4 when measured at theconventional temperatures of 100 F. and 210 F. When the viscosity indeximproving efficiency was calculated from measurements made at 100 F. and250 F., the etficiency was 1.8, indicating that this copolymer issuitable for use at temperatures higher than normally encountered inautomobile engines.

While the invention has been described in detail with reference tocertain specific embodiments, various changes and modifications whichfall within the spirit of the invention and scope of the appended claimswill become apparent to the skilled artisan. The invention is,therefore, only intended to be limited by the appended claims or theirequivalents wherein I have endeavored to claim all inherent novelty.

I claim:

1. A lubricating oil composition comprising a petroleum lubricating oiland dissolved therein in the range of 0.3 to 10 weight percent of ablock polymer having a molecular weight in the range of 50,000 to2,000,000 and composed solely of a hydrocarbon chain having a number ofalternate stereo-regular and amorphous segments, said stereo-regularsegments being of a poly alpha olefin having from 3 to 8 carbon atomsand being present in an amount sufiicient to give said polymer aviscosity index improving efiiciency of at least 1.0, said amorphoussegments being polymer segments of at least one lower alpha olefinhaving from 2 to 20 carbon atoms and amounting to at least 50 percent ofsaid molecular weight, said polymer being prepared in a Ziegler catalystsystem and said stereo-regular segments being of such an amount andnature so that if collectively joined in a polymer chain such polymerwould be oil-insoluble at a temperature below 0 C.

2. A lubricating oil composition comprising a petroleum lubricating oiland dissolved therein in the range of 0.3 to 10 weight percent of ablock polymer having a molecular weight in the range of 50,000 to2,000,000 and composed solely of a hydrocarbon chain having a number ofalternate stereo-regular and amorphous segments, said stereo-regularsegments being present in an amount sufficient to give said polymer aviscosity index improving efficiency of at least 1.0 and being composedof monomer units selected from the group consisting of propylene,styrene, butene-l, and hexene-l, said amorphous segments being composedof monomer units of at least one lower alpha olefin having from 2 to 20carbon atoms, said polymer being prepared in a Ziegler catalyst system,and said stereo-regular segments being of such an amount and nature sothat if collectively joined in a continuous polymer chain, such polymerwould be oilinsoluble at a temperature below 0 C.

3. The composition of claim 2 wherein said block polymer is a terpolymerof propylene, styrene and butene-l.

4. The composition of claim 2 wherein said block polymer is composed ofpropylene and butene-l monomer units.

5. The composition of claim 2 wherein said block polymer is composed ofethylene and propylene monomer units.

References Cited UNITED STATES PATENTS 2,895,915 7/1959 Hewett et al.252-59 2,917,458 12/1959 Morway et al. 252-59 3,378,606 4/1968 Kontos260-878 FOREIGN PATENTS 879,907 11/1961 Great Britain. 601,560 2/1960Italy. 615,048 10/1961 Italy.

OTHER REFERENCES Natta: Properties of Isoactic, Atactic and StereoblockHomopolymers, Random and Block Copolymers of a-Olefines, Journal ofPolymer Science, vol. XXXIV, PP. 531- 549 (1959).

MURRAY TILLMAN, Primary Examiner M. J. TULLY, Assistant Examiner U.S.Cl. X.R. 260--878

